Luckily Plaquenil maculopathy (damage to the central vision area or macula) is quite rare.  Much less than 1% of users develop this side effect, but there are several factors that can increase your chance of having vision damage due to the medication:

What does Plaquenil Toxicity Look Like?

During your yearly eye examination your eye doctor is looking for changes called "Bulls Eye Maculopathy". These are pigmentary changes typically in a target or ring pattern occurring right at the central vision area. Rarely enough, I have had a patient with confirmed plaquenil maculopathy.  She presented with 20/20 vision in both eyes, but her macula looked like this:


Unfortunately the pigmentary "bulls eye" changes that occur in plaquenil toxicity are a late stage finding, meaning that typically there has been structural damage and vision loss by the time these changes are observed on your eye exam.  As such, your doctor will be performing routine screenings with more advanced technology, separate from your comprehensive examination to ensure that there is no early damage developing.  These tests can include color vision screenings, central visual field tests, and periodically are required to include macular thickness scans (called OCT imaging), multifocal ERG, or fundus autofluorescence.  If you want to learn more about the required testing, and how often federal medical standards require that they be performed, follow the link to this post.

FUNDUS AUTOFLUORESCENCE showing photoreceptor damage in Plaquenil induced "Bulls Eye" Maculopathy via